We have a tendancy to freak out when anything unwanted pops up in the potting media of our indoor plants. There isn't mush-room, for starters, and then we're expected to determine if its a fun-guy or something more sinister. Truth is, mushrooms amongst your plant are often not a bad thing. [apologies for the puns. I can't stop myself]
What is a mushroom anyway?
Good place to start is actually understanding what a mushroom is and what its prescence usually means. They are not plants. These guys are part of the Fungi Kingdom. They reporoduce via spores, not seeds. These spores will spread through the air unobservable to us. The spores then develop into mycelium and the mycelium grows underground. The mushroom is the fruiting body from this mycelium - the reproductive structure that releases to spores.
Mycelium are an important part to plant health and vitality. Mycorrhizae is the symbiotic relationship between plants and fungi, where the mycelium attaches itself to the roots of the plant, assisting in nutirent and water uptake, while at the same time feeding off the carbohydrates produced by the plant during photosynthesis.
What sort of mushrooms are in my potting media?
The usual suspect is called Leucocoprinus birnbaumii. In fact, its so common in houseplants that its often refered to as Plantpot Dapperling or Flowerpot Parasol. It's small and comes in different shades of yellow - often starting as bright yellow when they first emerge from the soil then becoming paler as they grow.
These mushrooms are saprotrophic - meaning the feed off dead and decaying organic matter. As they lack chlorophyl, they can't photosynthesise and instead need to feed on things like leaves, insects, decaying bits of bark and wood. This is then released back into the potting mix as an easily accessible source of nutrients. Its a win win!
So what causes mushrooms to appear?
While the presence of the mushrooms themselves isn't a bad thing, they can be a signal that something else is not quiet right. As mushrooms thrive in moist, humid environments, their appearance could suggest that the potting media is too moist and the plant is potentially being overwatered. Check the potting media and adjust your watering if necessary. If you're sure the levels are ok, then the mushrooms are a bonus - they can improve the quality of the potting mix and help with the plant's nutrient intake.
I don't care how good they are, I want them gone.
Fair enough. You wanted a houseplant, not a mushroom colony. There are a few different options, all fairly straight forward.
Pick them out: This won't stop them coming back, but it will prevent them from releasing any more spores around the house and spreading to any more plants. Make sure you pick from the stalk, not the cap, to remove the while thing.
Adjust moisture or humidity levels: To prevent them thriving, simply remove the conditions that they need to do so. Adjust and reduce your watering routine and allow the potting mix to dry out a bit more between drinks.
Remove the top layer of soil: Scraping of the top layer of soil can work too, but as the results would be the same as if you picked them out, save yourself some soil and go with option one.
Repot: If you really do want to go full mushroom cleanse, then we recommend a complete repot. Pick a quality, free draining potting mix to reduce the chances of them coming back again.